1. Field of the Invention
The present invention relates to testing data receipt and transmission over cable plants using cable modems. More specifically, it relates to testing a head end complex in relation to a plurality of cable modems which connect to and send data to the head end complex and receive data from such head end complex.
2. Description of the Related Art
Cable modem technology is in a unique position to meet the demands of users seeking fast access to information services, the Internet and business applications, and can be used by those interested in cablecommuting (a group of workers working from home or remote sites whose numbers will grow as the cable modem infrastructure becomes increasingly prevalent). Not surprisingly, with the growing interest in receiving data over cable network systems, there has been an increased focus on performance, reliability, and improved maintenance of such systems. Cable companies are now typically full service providers of video, voice and data telecommunication services.
The Data over Cable Service Interface Specification (DOCSIS) protocol defines a standard for transmitting data over a cable system or plant. That is, DOCSIS defines communication between a head end or distribution hub and its associated cable modems. The head end is also referred to as a cable modem termination system or CMTS. The CMTS and its associated cable modems form part of a DOCSIS system. When the CMTS is upgraded or changed, it is then necessary to test the CMTS's function with respect to multiple associated cable modems.
FIG. 1 represents a conventional DOCSIS system 100 for testing a head end 102. As shown, the system 100 includes a head end 102 coupled with a plurality of cable modems 110. Typically, there are thousands of cable modems located at a single test site (not shown). The cable modems are coupled to a switch 112, which is in turn coupled with a traffic generator 114. The traffic generator 114 is typically configured to analyze data sent from the head end 102 to the cable modems 110, e.g., to determine whether the data is reliably received by the cable modems. The traffic generator 114 is also typically configured to generate traffic to be sent back to the CMTS.
A conventional cable modem test bed presents many challenges and disadvantages. For example, both the switch 112 and traffic generator 114 must be capable of supporting thousands of cable modems. Additionally, traditional DOCSIS modem test beds, such as the test bed of FIG. 1, can be very expensive and complex. A test bed with 10,000 modems will easily cost more than $1M, and require 78 racks (with 128 modems per rack) of space.
Therefore, it would be desirable to provide improved mechanisms for simulating a plurality of cable modems. Additionally, this improved simulation system would be capable of simulating operating conditions for each of the simulated cable modems, such as the distance from each cable modem to the head end and the power level of each cable modem.